Ignition system and control for fuel burner



y 7, 1965 J. L. LA POINTE ETAL 3,

IGNITION SYSTEM AND CONTROL FOR FUEL BURNER Filed Sept. 28, 1961 FIG.

:2 N J all m 0 \O In w INVENTORS I JOSEPH LEO 1.4 POtNTE JOHN J. FANNON.JR.

BY 61%: If??? SIGNAL LIGHT United States Patent 3,196,928 lIGNITliUNSYSTEM AND CONTROL FOR FUEL BURNER lioseph Leo La Pointe, Detroit, andJohn J. Fannon, J12,

Grosse Pointe Park, Mich, assignors to Hupp Corporaion, Cleveland, Ohio,a corporation of Virginia Filed Sept. 28, 1961, Ser. No. 141,479 6Claims. (Cl. 158-122) This invention relates to an ignition system orcontrol circuit for a burner, and especially to an automatic ignitionsystem for a gas burner operative to initiate fuel flow, ignite thefuel, and discontinue fuel flow in the event that combustion does nottake place.

This application is a continuation-in-part application of our co-pendingUnited States patent application Serial No. 844,387, filed October 5,1959, now Patent No. 3,155,- 145 granted November 3, 1964, and entitledControl Circuit for Gas Burner.

An object of the present invention is to provide a control circuit orignition system which minimizes the danger of escape of gas in explosivequantities or quantities sufficent to be poisonous to human beings.

A further object of the present invention is to provide a controlcircuit or ignition system for a gas burner.

A further object of the present invention is to provide an i nitionsystem, especially for a gas burner, to automatically ignite the burner.

A further object of the present invention is to provide an ignitionsystem having electronic means responsive to the combustion of gas in aburner to turn off the gas igniter.

A further object of the present invention is to provide an ignitionsystem that rapidly senses and responds without delay to the presence orabsence of a flame at the burner.

A further object of the present invention is to provide an ignitionsystem wherein the flow of fuel will be shut off if the burner fails toignite.

A further object of the present invention is to provide an ignitionsystem that will automatically re-ignite the burner after the flame hasbeen blown out.

A further object of the present invention is to provide an igintionsystem having means responsive to failure of combustion of fuel in aburner to actuate relay means and shut off a solenoid operated valve todiscontinue flow of fuel to the burner.

A further object of the present invention is to provide an ignitionsystem characterized by its compact construction; minimum number ofcomponent parts; low manufacturing cost; fail safe operation; ease ofuse; and long trouble-free wear life.

These and other objects of the present invention will become more fullyapparent by reference to the appended claims as the following detaileddescription proceeds in reference to the accompanying drawings wherein:

FIG. 1 is a schematic representation of a first form of the presentinvention; and

FIG. 2 is a schematic representation of a portion of a second form ofthe present invention.

FIG. 1 shows the first form of the invention. FIG. 2 shows a circuitcomponent adapted to be substituted in FIG. 1, for the component showntherein at the correspondingly numbered terminals, to provide saidsecond form to the invention with the remainder of FIG. 1. The firstform of the invention in FIG. 1 will be described in complete detailfirst before later describing the second form of the invention in FIG.2.

The control circuits, ignition systems, and methods of controllingignition of a burner in the present invention may be utilized in suchappliances as gas dryers, broilers, refrigerators, roasters, grills,ranges and furnaces; and in 3,196,928 Patented July 27, 1965 "ice avariety of industrial applications, such as industrial ovens, furnaces,die heaters, paint and baking ovens, and infrared space-heating units.Each is especially adapted for use on infra red radiant heater burnersof the type shown in the G. Schwank United States patents, Nos.2,775,294 and 2,870,830. When used in industrial applications, each maybe readily cycled for repetitive production processes.

FIG. 1 discloses a conventional solenoid operated gas valve 14 forsupplying and controlling the flow of combustible fluid fuel, such asgas, from supply line 18A to fluid fuel burner means 18. Air isaspirated into burner 18 by the gas and burned adjacent one surface ofthe burner to form flame 19. Burner housing 18 is made of metal or otherelectrically conductive material. Gas or fuel valve 14 is a conventionalshut-off valve having valve element 14A to open or close a port tocontol the flow of gas. Valve element 14A is urged to the valve closedposition by a spring (not shown). Solenoid 13, upon energization, iseffective to open valve element 14A in valve 14 against the action ofthe spring into the valve open position, while de-energization ofsolenoid 13 permits the spring to move valve element 14A to the valveclosed position.

Time delay relays V2 and V3 are of a conventional type in which heaterelements 16 and 11 therein respectively are provided to heat to apre-selected temperature in a pre-selected time so as to open or closeassociated respective contacts or switches 15 and 12 at the pre-selectedtime and temperature.

Although any suitable circuit components may be used, it has been foundin one suitable installation that a proper mode of operation is achievedby using components of the following sizes: transformer T1 has a 115volt, 60 cycle primary winding or coil Tl-P, 190 volt A.C. acrosssecondary terminals T1-1 and T1-2 at no currents conditions, 6.3 volts 2amps across secondary terminals Til-3 and T1-4, 24 volts acrosssecondary terminals T14 and T1-5, ma. across terminals T1-4 and T1-6,160 volts across terminals T1-5 and T1-6, and a secondary coil T1-5having terminals Til-1, T12, T1-3, T1-4, T1-5, and T16; glow coiligniter transformer T3 has a volts, 2.5 amps primary coil and a 2.5volts, 11 amps secondary coil; high resistance Z1 is a 4.7 megohm /2watt resistor; grid protector resistance Z2 is a 240K ohms /2 wattresistor; capacitance C1 is 0.1 mfd., 400 V. DO: igniter coil 10 is aNichrome heater element glow coil; thyratron tube V1 is a 2D21thyratron, or any equivalent electronic valve; and probe 20 is a metalprobe constructed of Inconel or other suitable material.

The mode of operation should be readily apparent after considering thefollowing description.

Closing main switch S1 energizes the primary and secondary coils oftransformer T1 and igniter glow coil 10, positioned adjacent burner 18for causing flame 19. Alternating current power is supplied through AC.power lines L1, L2 to primary coil T1-P and secondary coil T1-S oftransformer T1 after closing main switch S1 for supplying power to tubeV1. Closing switch S1 also energizes or supplies alternating currentpower to igniter glow coil or igniter 10 by forming Circuit No. 1through line L1, transformer T3, igniter glow coil 10, normally closedcontact R1-1 of relay R1 as a switch means in igniter energizingcircuit, and line L2.

Since tube V1 disclosed herein requires approximately 10 to 15 secondswarmup time before it can operate, a suitable time delay is provided inthe circuit by keeping open contact 12 of time delay relay tube V3 toprevent power being applied to gas valve solenoid 13 until after warmuphas occurred. Closing main switch S1 energizes time delay relay tube V3by forming Circuit No. 2 through probe element means 20.

line L1, heater element 11 of time delay relay tube V3, and line L2.After the to seconds time delay has elapsed, heater element 11 of tubeV3 closes its normally open contact 12: (1) to energize solenoid 13 toopen gas control valve 14 to permit gas to flow from gas line 18A intoburner 18 by forming Circuit No. 3 electrically connected in parallelwith primary coil T1P of transformer T1 through line L1, normally opencontact 12 now closed, normally closed contact 15, valve solenoid 13,and line L2; and (2) to energize time delay relay tube V2 by formingCircuit No. 4 through line L1, normally open contact 12 now closed,heater element 16 of tube V2, normally closed contact R1-1 of relay R1,and line L2.

Now, energized igniter 10 will ignite the gas mixture now permitted toflow from burner 18 through open valve 14 and will produce flame 19.

After the gas is ignited, flame 19 completes an electrical path causingthyratron tube V1 to conduct, relay R1 to be energized, and igniter 10and time delay relay heater element 16 to be de-energized. Tube V1 hascathode heater 22 energized by a circuit from transformer secondarywinding terminals T1-3 and T1-4. Flame 19 forms Circuit No. 5 throughseries connected transformer tap T1-1, resistance Z1, junction Z4,burner housing 13, flame 19, flame sensing element means or probelocated adjacent burner 18 contiguous to or in flame 19 from burner 18,and transformer secondary tap T1-6. Circuit No. 5 is energized bysecondary coil T1-S and electrically connected to grid at junction Z4.The voltage pulse or the potential at junction Z4 produced by CircuitNo. 5 is now sufiiciently positive relative to cathode 23, because ofthe IR drop across resistance Z1, so that a glow discharge takes placebetween cathode 23 and starter anode or grid 25 so the gas is ionized inthyratron tube V1 and the tube conducts, during each half cycle thatanode 24 is positive, so electronic valve V1 is actuated to energizerelay R1 by forming Circuit No. 6 energized by secondary coil Tl-Sthrough transformer secondary terminal T1-5, cathode 23 of thyratrontube V1, anode 24 of tube V1, relay coil R1-C of relay R1, andtransformer secondary terminal T1-6. Sensing element 20, electricallyconnected to grid 25, thus senses the presence of flame 19 by conductionof an electrical current along a path through flame 19 to control theconduction action of tube V1 by grid 25. Rectifier or diode 26, locatedin series with thyratron V1, is in parallel with relay coil Rl-C toprevent relay chatter because tube V1 conducts only during the positivehalf cycles, but any suitable unidirectional electronic valve, such as acondenser, may be so placed in parallel with relay coil R1-C for thissame purpose, Energizing relay coil R1-C opens switch means or normallyclosed relay contact Rl-l now: (1) to break Circuit No, l to de-energizeand cut 011 power to igniter 10 for conservation purposes when a flame19 is present and thyratron V1 is energized, and (2) to break CircuitNo. 4 to de-energize heater element 16 of time delay relay tube V2. Gasvalve 14 is open, igniter 16 is de-energized, heater element 16 of timedelay tube V2 is de-energized, and flame 19 maintains this condition ofoperation.

Here, two electrode elements are provided in Circuit No. 5, includingburner housing element means 18 and If desired, a second probe,electrode or structural element means, similar to probe 20, can belocated in flame 19 and directly electrically connected to junction Z4and ground G1 with burner 18 eliminated from Circuit No. 5.

If flame 19 goes out, tube V1 stops conducting, relay R1 isde-energized, igniter 10 is re-energized, and heater element 16 of timedelay relay tube V2 is re-energized. If flame 19 goes out, lack of flame19 causes sensing element 20 to control the action of tube V1 bybreaking Circuit No. 5 so that the positive potential at junction Z4 isreduced to reduce the positive bias on grid 25 of tube V1 to preventtube V1 from conducting. Since tube V1 stops conducting, Circuit No. 6is broken to deenergize relay coil Rl-C and close its normally closedcontact R11. Closing switch means or relay contact R1-1 now: (1)energizes or applies power to igniter 10 by reforming Circuit No. 1 whenflame 19 is absent, and (2) energizes heater element 16 of time delayrelay tube V2 by reforming heater element energizing Circuit No. 4.

If flame 19 is absent, burner 18 does not re-ignite, or flame 19 is notrestored within a predetermined period of time established by thermaltime delay switch means or relay tube V2, gas valve 14 is closed. Aftertime delay relay tube V2 times out, its energized and heated heaterelement 16 opens its normally closed bimetal switch or contact 15located in valve energizing Circuit No. 3 to break Circuit No. 3 tode-energize solenoid 13 and thus to close gas valve 1-4 to cut off thesupply of fuel to burner 18.

It should also be readily apparent that if, when Circuit No. 4 was firstformed as first described heretofore, flame 19 was not produced withinthe predetermined period of time established by heater element 16 oftime delay relay tube V2, heater element 16 opens normally closedcontact 15 to break Circuit No. 3 to de-energize solenoid coil 13 toclose valve 14 in the same manner to shut off the supply of gas toburner 18.

The second form of the invention is shown in FIG. 2. It is exactly thesame as the FIG. 1 form except that the circuitry in FIG. 2 betweenterminals 51, 52, 53 and 54 (including manually operated switch 55 andneon glow lamp 56 or other suitable warning light) is substituted fortubes V2 and V3 in FIG. 1 at terminals 51, 52, 53 and 54. The sequenceof operation and of circuit forming and breaking occurs the same asbefore described but with the following exceptions. First, tube warmupCircuit No. 2 is not used to close switch 12, and Circuit No. 3 is nownot formed until after switch 55 is manually closed so that the gasvalve and ignition are manually operated, such as on a domestic oven orboiler igniter. Second, if any of these conditions: (1) flame 19 goesout after once lit, or (2) flame 19 is not originally produced haveoccurred so as to break sequentially Circuits Nos. 5 and 6 tode-energize relay coil R1-C, normally closed relay contact R1-1 willclose to reform: (1) Circuit No. 4 so lamp 56 will now be energized,instead of heater element 16 of tube V2, to indicate lack of flame 19and to indicate ignition on to the apparatus operator, and (2) CircuitNo. 1 to re-energize igniter 10. After lamp 56 has been lit for apredetermined period of time, the operator may manually open switch 55to break Circuit No. 3 to de-energize solenoid 13 to close gas valve 14in the same manner as heating of element 16 in FIG. 1 automaticallyopened switch 15 in tube V2 to break Circuit No. 3 after the time delay.

It may now be readily appreciated that the control circuits and ignitionsystems in FIGS. 1 and 2 invention forms are effective as safeguards toassure that gas bumer 18 is operating properly when gas valve 14 isopen, and to automatically ignite and re-ignite burner 18. The apparatusis simple in construction, requires a minimum number of operating parts,is compact, operates quickly without undue delay, is fail-safe in thatfailure of substantially any of the component parts will operate todiscontinue the flow of gas to burner 18 and require trouble-shooting ofthe circuit to locate and repair the fault, and has a substantiallylong, trouble-free wear life.

The invention may be embodied in other specific forms without departingfrom the spirit or essential charactcristics thereof. The presentembodiments are, therefore, to be considered in all respects asillustrative and not restrictive with the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by U.S. Letters Patent is:

1. An ignition and control for a burner system, comprising a transformerhaving a primary coil and a secondary coil, an igniter positionedadjacent said burner and adapted to be supplied with current to ignitesaid burner, a thyratron, said secondary coil providing power by acircuit means to said thyratron, a solenoid operated fuel valve forcontrolling flow of fuel to said burner, a valve energizing circuit inparallel with said primary coil electrically connected to andcontrolling the solenoid of said fuel valve, a sensing element adaptedto be positioned adjacent the burner to sense the presence of a flame,said sensing element being electrically connected to the grid of saidthyratron for controlling the conduction of said thyratron, a relay,circuit means for energizing said relay by said thyratron when thesensing element responsive to the presence of a flame causes saidthyratron to conduct, switch means in said igniter circuit opened bysaid relay when said relay is energized to thereby de-energize theigniter upon the thyratron becoming energized by said sensing element,and closed by said relay when said relay is de-energized for applyingpower to said igniter when the thyratron is de-energized in the absenceof a flame thermal time delay switch means including a heater elementand a normally closed switch adapted to be opened by energizing saidheater element for a predetermined period of time, said normally closedswitch being in the valve energizing circuit, and switch means in theenergizing circuit of said heater element closed by said relay when saidrelay is de-energized so that the normally closed switch is opened tode-energize the solenoid and to close said fuel valve in the event thatthe burner either does not initially ignite or does not re-ignite withina predetermined period of time.

2. An ignition and control for a burner system, comprising a transformerhaving a primary coil and a secondary coil, an igniter positionedadjacent said burner and adapted to be supplied with current to ignitesaid burner, a thyratron, said secondary coil providing power by acircuit means to said thyratron, a solenoid operated fuel valve forcontrolling flow of fuel to said burner, a valve energizing circuit inparallel with said primary coil electrically connected to andcontrolling the solenoid of said fuel valve, a sensing element adaptedto be positioned adjacent the burner to sense the presence of a flame,said sensing element being electrically connected to the grid of saidthyratron for controlling the conduction of said thyratron, a relay,circuit means for energizing said relay by said thyratron when thesensing element responsive to the presence of a flame causes saidthyratron to conduct, switch means in said igniter circuit opened bysaid relay when said relay is energized to thereby de-energize theigniter upon the thyratron becoming energized by said sensing elementand closed by said relay when said relay is tie-energized for applyingpower to said igniter when the thyratron is de-energized in the absenceof a flame, thermal time delay switch means including a heater elementand a normally closed switch adapted to be opened by energizing saidheater element for a predetermined period of time, said normally closedswitch being in the valve energizing circuit, switch means in theenergizing circuit of said heater element closed by said relay when saidrelay is deenergized so that the normally closed switch is opened tode-energize the solenoid and to close said fuel valve in the event thatthe burner either does not initially ignite or does not re-ignite Withina predetermined period of time, a unidirectional electronic valve inparallel with said relay and in series with said thyratron in the relayenergizing circuit from said thyratron.

3. A system, as set forth in claim 2, with said sensing elementcomprising a probe adapted to be located in said flame; and a resistancein series with said probe and flame d forming a circuit energized bysaid secondary coil and electrically connected to the grid of saidthyratron for controlling the conduction of said thyratron.

4. An ignition and control for a burner system, comprising a transformerhaving a primary coil and a secondary coil, an igniter positionedadjacent said burner and adapted to be supplied with current to ignitesaid burner, a thyratron, said secondary coil providing power by acircuit means to said thyratron, a solenoid operated fuel valve forcontrolling flow of fuel to said burner, a valve energizing circuit inparallel with said primary coil electrically connected to andcontrolling the solenoid of said fuel valve, a sensing element adaptedto be positioned adjacent the burner to sense the presence of a flame,said sensing element being electrically connected to the grid of saidthyratron for controlling the conduction of said thyratron, a relay,circuit means for energizing said relay by said thyratron when thesensing element responsive to the presence of a flame causes saidthyratron to conduct, switch means in said igniter circuit opened bysaid relay when said relay is energized to thereby deenergize theigniter upon the thyratron becoming energized by said sensing elementand closed by said relay when saidrelay is dc-energized for applyingpower to said igniter when the thyratron is de-energized in the absenceof a flame, thermal time delay switch means including a heater elementand a normally closed switch adapted to be opened by energizing saidheater element for a predetermined period of time, said normally closedswitch being in the valve energizing circuit, switch means in theenergizing circuit of said heater element closed by said relay when saidrelay is dc-energized so that the normally closed switch is opened tode-energize the solenoid and to close said fuel valve in the event thatthe burner either does not initially ignite or does not re-ignite withina predetermined period of time, said sensing element sensing thepresence of a flame by an electrical path through said flame to providethe sole means to control the conductive action of said thyratron.

5. An ignition and control apparatus for a burner producing a flame,comprising a transformer having a primary coil and a secondary coil, anignitor positioned adjacent to said burner and adapted to be suppliedwith current to ignite said burner, a thyratron supplied with power by acircuit means from said secondary coil, a fuel control means forcontrolling flow of fuel to said burner, fuel control means energizingcircuit in parallel with said primary coil electrically connected to andcontrolling the fuel control means, a flame probe adjacent to butseparated from said burner and positioned to contact said flame whensaid burner is in operation, said probe being electrically connected tothe grid of said thyratron for controlling the conduction of saidthyratron, a relay, circuit means for first energizing said relay bysaid thyratron after flame at the burner completes a circuit throughsaid probe to cause said thyratron to conduct, switch means in saidignitor circuit first opened by said relay when the relay is energized,a thermal time delay means including a heater element in anormallyclosed switch adapted to be opened by energizing said heaterelement for a predetermined period of time, said normally-closed switchbeing in the circuit including said fuel control means, means forenergizing said heater element with said ignitor so that thenormally-closed switch is opened to de-energize and close said fuelcontrol means in the event that the burner either does not initiallyignite or does not reignite after a pre-determined period of time, asecond thermal time delay means including a second heater and a normallyopen switch adapted to be closed by energizing said second heater for apredetermined period of time, said normally open switch being in thecircuit including the first-mentioned thermal time delay means, saidsecond heater being in said energizing circuit in parallel with saidprimary coil.

6. An ignition and control apparatus for a burner producing a flame,comprising a transformer having a primary coil and a secondary coil, anignitor positioned adjacent to said burner and adapted to be suppliedwith current to ignite said burner, 21 thyratron supplied with power bya circuit means from said secondary coil, 21 fuel control means forcontrolling flow of fuel to said burner, fuel control means energizingcircuit in parallel with said primary coil electrically connected to andcontrolling the fuel control means, a flame probe adjacent to butseparated from said burner and positioned to contact said flame whensaid burner is in operation, said probe being electrically connected tothe grid of said thyratron for controlling the conduction of saidthyratron, a relay, circuit means for first energizing said relay bysaid thyratron after flame at the burner completes a circuit throughsaid probe to cause said thyratron to conduct, switch means in saidignitor circuit first opened by said relay when the relay is energized,a manually-operated switch in said circuit through said fuel controlmeans, a pilot lamp, and means energizing said pilot lamp with saidignitor.

References Cited by the Examiner UNITED STATES PATENTS 1,899,744 2/33Breisky, et a1 158-28 1,936,784 11/33 Diamond 158-28 2,162,501 6/39Draper 158-28 2,243,071 5/41 Crago 158-28 2,388,124 10/45 Crews 158-282,720,614 10/55 Cairns 158-130 X 2,761,625 9/56 Dymski 158-28 X2,870,329 1/59 Aubert 158-123 2,964,102 12/60 Cassell, et a1. 158-1252,981,324 4/61 DeZiel 158-125 JAMES W. WESTHAVER, Primary Examiner.

MEYER PERLIN, Examiner.

6. AN INGITION AND CONTROL APPARATUS FOR A BURNER PRODUCING A FLAME,COMPRISING A TRANSFORMER HAVING A PRIMARY COIL AND A SECONDARY COIL, ANIGITOR POSITIONED ADJACENT TO SAID BURNER AND ADAPTED TO BE SUPPLIEDWITH CURRENT TO INGNITE SAID BURNER, A THYRATRON SUPPLIED WITH POWER BYA CIRCUIT MEANS FROM SAID SECONDARY COIL, A FUEL CONTROL MEANS FORCONTROLLING FLOW OF FUEL TO SAID BURNER, FUEL CONTROL MEANS, ENERGIZINGCIRCUIT IN PARALLEL WITH SAID PRIMARY COIL ELECTRICALLY CONNECTED TO ANDCONTROLLING THE FUEL CONTROL MEANS, A FLAME PROBE ADJACENT TO BUTSEPARATED FROM SAID BURNER AND POSITIONED TO CONTACT SAID FLAME WHENSAID BURNER IS IN OPERATION, SAID PROBE BEING ELECTRICALLY CONNECTED TOTHE GRID SAID THYRATRON FOR CONTROLLING THE CONDUCTION OF SAIDTHYRATRON, A RELAY, CIRCUIT MEANS FOR FIRST ENERGIZING SAID RELAY BYSAID THYRATRON SAID PROBE TO CAUSE SAID THYRATRON TO CONCUIT THROUGHSAID PROBE TO CAUSE SAID THYRATRON TO CONDUCT, SWITCH MEANS IN SAIDIGNITOR CIRCUIT FIRST OPENED BY SAID RELAY WHEN THE RELAY IS ENERGIZED,A MANUALLY-OPERATED SWITCH IN SAID CIRCUIT THROUGH SAID FUEL CONTROLMEANS, A PILOT LAMP, AND MEANS ENERGIZING SAID PILOT LAMP WITH SAIDIGNITOR.